RACM – means Reasonably Available Control Measure as defined by USEPA in accordance with Section 172(c)(1) of the CAA and subsequent rules and guidance. In general, USEPA interprets the RACM provision to require a demonstration that the state has adopted all reasonable measures (including RACT) to meet RFP requirements and to demonstrate attainment as expeditiously as practicable. They also require an additional analysis to determine if there are any additional RACM that will advance the attainment date by at least one year. They further interpret RACM to mean measures that are technologically and economically feasible, do not cause substantial widespread and long term adverse impact, or are absurd, unenforceable or impracticable.

RACT – means Reasonably Available Control Technology as defined by USEPA in accordance with CAA Sections 184(b)(1) and 184(b)(2). RACT is for all existing VOC and NOx source categories covered by a Control Techniques Guideline (CTG), and for all other major sources of VOC and NOx, including those covered by an Alternative Control Techniques (ACT). RACT is defined by the USEPA as the lowest emission limitation that a particular source is capable of meeting by the application of control technology that is reasonably available considering technological and economic feasibility.

Regional Greenhouse Gas Initiative (RGGI) – A cooperative effort by Northeastern and Mid-Atlantic states to reduce carbon dioxide emissions to control interstate transport and international transport of greenhouse gases.

Reformulated gasoline (RFG) – specially refined gasoline
with low levels of smog-forming volatile organic compounds
(VOCs) and the low levels of hazardous air pollutants. The
1990 Clean Air Act requires sale of reformulated gasoline in
the nine smoggiest areas. Reformulated gasolines were
sold in several smoggy areas even before the 1990 Clean Air
Act was passed.

RFP – means Reasonable Further Progress as defined by USEPA as the emissions reductions required under CAA Sections 172(c)(2), 182(b)(1), 182(c)(2)(B) and (c)(2)(C). RFP is the annual incremental reductions in certain air pollutant emissions as demonstrated in the State Implementation Plans that the USEPA requires to provide for the attainment of the applicable national ambient air quality standards by the statutory deadline.

RTP – means Regional Transportation Plan. The federally
mandated long-range transportation plan for the region. It
sets out a vision for development of the transportation system
over the next twenty years and serves as an investment guide
for the region. Updated every three years.

RH – means Regional Haze. The haze produced by
a multitude of sources and activities, which emit fine particles
and their precursors across a broad geographic area. The U.S.
regulations require states to develop plans to reduce the regional
haze that impairs visibility in Class I areas.

ROP – means Rate of Progress, which is a subset of RFP. USEPA defines ROP as “the 15 percent progress reductions in VOC emissions over the first six years required under CAA section 182(b)(1).”

RRF – means Relative Reduction Factor, which for ozone means the ratio of a photochemical model’s future year ozone estimates to baseline year ozone estimates at each ozone monitor.